America's wealth landscape is in flux. In recent years, a new segment of wealthy Americans has emerged, according to a new white paper recently released by Nielsen Claritas.

Known as the "New Mass Affluent," members of this group have amassed assets of more than $100,000 each, though most of these baby boomers were born into middle class households. By 2007, the group represented 19% of all households in the U.S. By 2012, the New Mass Affluent is expected to grow to account for at least 20% of all American households.

Often underserved by financial services companies, the group represents a significant opportunity for that industry, Nielsen's white paper argues -- especially now, as its members approach retirement and prepare to roll over 401(k) funds into retirement accounts.